====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc7-syzkaller-ga5806cd506af #0 Not tainted ------------------------------------------------------ syz.0.16/6544 is trying to acquire lock: ffff88805d6f4b58 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:877 [inline] ffff88805d6f4b58 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow fs/namei.c:1833 [inline] ffff88805d6f4b58 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: walk_component+0x345/0x5b0 fs/namei.c:2138 but task is already holding lock: ffffffff8e27ef88 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:607 [inline] ffffffff8e27ef88 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xec/0x300 kernel/params.c:586 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (param_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 ieee80211_rate_control_ops_get net/mac80211/rate.c:220 [inline] rate_control_alloc net/mac80211/rate.c:266 [inline] ieee80211_init_rate_ctrl_alg+0x18d/0x6b0 net/mac80211/rate.c:1015 ieee80211_register_hw+0x2124/0x4140 net/mac80211/main.c:1533 mac80211_hwsim_new_radio+0x3034/0x54d0 drivers/net/wireless/virtual/mac80211_hwsim.c:5559 init_mac80211_hwsim+0x44e/0x900 drivers/net/wireless/virtual/mac80211_hwsim.c:6911 do_one_initcall+0x120/0x6e0 init/main.c:1257 do_initcall_level init/main.c:1319 [inline] do_initcalls init/main.c:1335 [inline] do_basic_setup init/main.c:1354 [inline] kernel_init_freeable+0x5c2/0x900 init/main.c:1567 kernel_init+0x1c/0x2b0 init/main.c:1457 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (rtnl_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 cgrp_css_online+0xa2/0x1f0 net/core/netprio_cgroup.c:157 online_css+0xb2/0x350 kernel/cgroup/cgroup.c:5607 css_create kernel/cgroup/cgroup.c:5691 [inline] cgroup_apply_control_enable+0x6cd/0xc70 kernel/cgroup/cgroup.c:3282 cgroup_mkdir+0x39a/0x1160 kernel/cgroup/cgroup.c:5886 kernfs_iop_mkdir+0x10b/0x190 fs/kernfs/dir.c:1266 vfs_mkdir+0x593/0x8c0 fs/namei.c:4359 do_mkdirat+0x304/0x3e0 fs/namei.c:4392 __do_sys_mkdirat fs/namei.c:4409 [inline] __se_sys_mkdirat fs/namei.c:4407 [inline] __x64_sys_mkdirat+0x83/0xb0 fs/namei.c:4407 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (cgroup_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 cgroup_lock include/linux/cgroup.h:369 [inline] cgroup_kn_lock_live+0x116/0x520 kernel/cgroup/cgroup.c:1675 cgroup_rmdir+0x20/0x2b0 kernel/cgroup/cgroup.c:6090 kernfs_iop_rmdir+0x100/0x170 fs/kernfs/dir.c:1284 vfs_rmdir fs/namei.c:4454 [inline] vfs_rmdir+0x206/0x690 fs/namei.c:4431 do_rmdir+0x2e8/0x3c0 fs/namei.c:4509 __do_sys_rmdir fs/namei.c:4528 [inline] __se_sys_rmdir fs/namei.c:4526 [inline] __x64_sys_rmdir+0xc5/0x110 fs/namei.c:4526 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->i_mutex_dir_key#6){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read+0x9b/0x480 kernel/locking/rwsem.c:1524 inode_lock_shared include/linux/fs.h:877 [inline] lookup_slow fs/namei.c:1833 [inline] walk_component+0x345/0x5b0 fs/namei.c:2138 lookup_last fs/namei.c:2636 [inline] path_lookupat+0x17e/0x780 fs/namei.c:2660 filename_lookup+0x224/0x5f0 fs/namei.c:2689 kern_path+0x35/0x50 fs/namei.c:2822 lookup_bdev+0xd8/0x280 block/bdev.c:1205 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1078 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2+0x317/0xe10 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0xbd/0x110 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x199/0x300 kernel/params.c:588 module_attr_store+0x58/0x80 kernel/params.c:918 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x5ba/0x1180 fs/read_write.c:684 ksys_write+0x12a/0x240 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#6 --> rtnl_mutex --> param_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(param_lock); lock(rtnl_mutex); lock(param_lock); rlock(&type->i_mutex_dir_key#6); *** DEADLOCK *** 5 locks held by syz.0.16/6544: #0: ffff888021ea37b8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1213 #1: ffff88807cd7a420 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x240 fs/read_write.c:736 #2: ffff88807826a088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 #3: ffff88814cbc90f8 (kn->active#4){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2b2/0x510 fs/kernfs/file.c:326 #4: ffffffff8e27ef88 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:607 [inline] #4: ffffffff8e27ef88 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xec/0x300 kernel/params.c:586 stack backtrace: CPU: 0 UID: 0 PID: 6544 Comm: syz.0.16 Not tainted 6.15.0-rc7-syzkaller-ga5806cd506af #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read+0x9b/0x480 kernel/locking/rwsem.c:1524 inode_lock_shared include/linux/fs.h:877 [inline] lookup_slow fs/namei.c:1833 [inline] walk_component+0x345/0x5b0 fs/namei.c:2138 lookup_last fs/namei.c:2636 [inline] path_lookupat+0x17e/0x780 fs/namei.c:2660 filename_lookup+0x224/0x5f0 fs/namei.c:2689 kern_path+0x35/0x50 fs/namei.c:2822 lookup_bdev+0xd8/0x280 block/bdev.c:1205 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1078 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2+0x317/0xe10 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0xbd/0x110 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x199/0x300 kernel/params.c:588 module_attr_store+0x58/0x80 kernel/params.c:918 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x5ba/0x1180 fs/read_write.c:684 ksys_write+0x12a/0x240 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff568f8cda9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff569e84038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007ff5691a5fa0 RCX: 00007ff568f8cda9 RDX: 0000000000000003 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 00007ff56900e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff5691a5fa0 R15: 00007ffdbd20fae8 block2mtd: error: cannot open device 3QI